move gotd fork into repo. (#111)

- update to latest telegram layer
- remove some references to fields in tg.Entities that don't exist in
the schema
- originally added here:
https://github.com/beeper/td/commit/820929062a2ba0104397bc01235ab58a9cff780e
  - referenced here
-
https://github.com/mautrix/telegramgo/commit/124f0967ed195b5a380c9bd02e170ada9710dde3
-
https://github.com/mautrix/telegramgo/commit/4205047aab2e0639217148b5d125bfaab668bd8e

pkg/gotd/telegram/updates/internal/e2e/handler.go

@@ -0,0 +1,60 @@
+package e2e
+
+import (
+	"context"
+	"sync"
+
+	"go.mau.fi/mautrix-telegram/pkg/gotd/tg"
+)
+
+// Handler handles updates.
+type handler struct {
+	messages *messageDatabase
+	ents     *Entities
+	mux      sync.Mutex
+}
+
+func newHandler() *handler {
+	return &handler{
+		messages: &messageDatabase{
+			channels: make(map[int64][]tg.MessageClass),
+		},
+		ents: NewEntities(),
+	}
+}
+
+func (h *handler) Handle(ctx context.Context, u tg.UpdatesClass) error {
+	switch u := u.(type) {
+	case *tg.Updates:
+		return h.handleUpdates(NewEntities().FromUpdates(u), u.Updates)
+	case *tg.UpdatesCombined:
+		return h.handleUpdates(NewEntities().FromUpdates(u), u.Updates)
+	default:
+		panic(u)
+	}
+}
+
+// HandleUpdates handler.
+func (h *handler) handleUpdates(ents *Entities, upds []tg.UpdateClass) error {
+	h.mux.Lock()
+	defer h.mux.Unlock()
+
+	h.ents.Merge(ents)
+	for _, u := range upds {
+		switch u := u.(type) {
+		case *tg.UpdateNewMessage:
+			h.messages.common = append(h.messages.common, u.Message)
+		case *tg.UpdateNewEncryptedMessage:
+			h.messages.secret = append(h.messages.secret, u.Message)
+		case *tg.UpdateNewChannelMessage:
+			channelID := u.Message.(*tg.Message).PeerID.(*tg.PeerChannel).ChannelID
+			msgs := h.messages.channels[channelID]
+			msgs = append(msgs, u.Message)
+			h.messages.channels[channelID] = msgs
+		default:
+			panic("unexpected update type")
+		}
+	}
+
+	return nil
+}